Methods and systems for treating carbonaceous materials

ABSTRACT

A method for treating a carbonaceous material comprising heating a carbonaceous material to form a mixture of the carbonaceous material and a tar; cooling the mixture of the carbonaceous material and the tar; and coating a surface of the carbonaceous material with the tar to form a tar-coated carbonaceous material, and a system related thereto.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to methods for treatingcarbonaceous materials, and more particularly to methods for treatingcarbonaceous materials which improve the removal of ash fromcarbonaceous materials, and systems related thereto.

Different technologies are used to generate energy from organic orfossil-based carbonaceous materials such as coal. Different types ofcoal, such as lignite, or brown coal, subbituminous coal, bituminouscoal, or black coal, anthracite and/or graphite, are utilized in energyproducing systems. These different types of coal are categorized, orranked, according to their particular physical properties, e.g.,“low-rank coal” and “high-rank coal”.

Varying amounts of ash are present in naturally occurring carbonaceousmaterials such as coal. Ash is the non-combustible residue of mineralmatter present in the carbonaceous material. Some coal materials have anash content of greater than 20%, or even greater than 50%. The greaterthe ash content of the raw coal material, the lower amount of coal thatwill be available for energy production. High ash contents are alsogenerally undesirable because of the potential for contamination of theequipment used in the energy production due to impurities present in theash.

Carbonaceous materials such as coal are therefore subjected to an ashremoval treatment on. Ash is separated from coal based upon differencesbetween the inherent surface properties of the ash, which ishydrophilic, i.e., attracts water, and the coal, which is hydrophobic,i.e. repels water. Coal washing and/or flotation columns, for example,are used to separate the ash from the coal by taking advantage of thehydrophilic nature of the surface of the ash and the hydrophobic natureof the surface of the coal. Therefore, the amount of ash which isremoved from coal using an ash-removal treatment is limited by theextent of these inherent surface properties.

Consequently, the ash content of coal materials which have a significantamount of ash cannot be sufficiently lowered using an ash removaltreatment without the use of one or more additives. Various additivesare employed in order to enhance the separation of the hydrophobic coalfrom the hydrophilic ash in order to provide a coal material withsuitably low ash content for use in energy production. Such additivesrepresent a significant cost in materials and/or process efficiency.

It is therefore desirable to provide a method for treating carbonaceousmaterials in order to improve the removal of ash from carbonaceousmaterials, and systems related thereto, which solve one or more of theaforementioned problems.

BRIEF DESCRIPTION OF THE INVENTION

According to one aspect of the invention, a method for treating acarbonaceous material comprises heating a carbonaceous material to forma mixture of the carbonaceous material and a tar; cooling the mixture ofthe carbonaceous material and the tar, and coating a surface of thecarbonaceous material with the tar to form a tar-coated carbonaceousmaterial.

According to another aspect of the invention, a system for treating acarbonaceous material comprises a heating region, the heating regionbeing operative to heat a carbonaceous material to form a mixture of thecarbonaceous material and a tar; a cooling region, the cooling regionbeing operative to cool the mixture of the carbonaceous material and thetar and to coat a surface of the carbonaceous material with the tar toform a tar-coated carbonaceous material.

These and other advantages and features will become more apparent fromthe following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter, which is regarded as the invention, is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features, and advantages ofthe invention are apparent from the following detailed description takenin conjunction with the accompanying drawings in which:

FIG. 1 is a block flow diagram of a method for treating a carbonaceousmaterial; and

FIG. 2 is a schematic diagram of a system for treating a carbonaceousmaterial.

The detailed description explains embodiments of the invention, togetherwith advantages and features, by way of example with reference to thedrawings.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments described herein generally relate to methods for treating acarbonaceous material and systems related thereto. A method for treatinga carbonaceous material is provided to modify the surface of thecarbonaceous material in order to improve the separation of ash from thecarbonaceous material.

Referring to FIG. 1, the method for treating a carbonaceous materialcomprises heating a carbonaceous material. Upon heating, a tar isreleased from the carbonaceous material to form a mixture of thecarbonaceous material and the tar. The method further comprises coolingthe mixture of the carbonaceous material and the tar. Upon cooling, atleast a portion of the tar released from the carbonaceous material coatsat least a portion of a surface of the carbonaceous material to form atar-coated carbonaceous material.

The carbonaceous material is any carbon-rich and/or hydrocarbon-basedmaterial. In one embodiment, the carbonaceous material comprises coal.In another embodiment, the carbonaceous material comprises low-rankcoal, high-rank coal, or a combination comprising at least one of theforegoing. In yet another embodiment, the carbonaceous materialcomprises lignite, or brown coal, subbituminous coal, bituminous coal,or black coal, anthracite, graphite or a combination comprising at leastone of the foregoing.

In one embodiment, the carbonaceous material comprises crushed coal. Thecoal is crushed using any appropriate crushing method and/or equipment,such as for example, a coal crusher, a coal shredder and/or a coalgrinder. The coal is ground, crushed and/or shredded into smallerparticles prior to heating.

The carbonaceous material comprises varying amounts of ash, includingfor example, high ash, e.g., greater than about 30% total ash content,and low ash, e.g., less than about 30% total ash content. In oneembodiment, the carbonaceous material has a total ash content of about10% to about 80% prior to heating. In another embodiment thecarbonaceous material has a total ash content of about 10% to about 50%prior to heating. In yet another embodiment, the carbonaceous materialhas a total ash content of about 30% to about 50% prior to heating.

The carbonaceous material is heated as a solid or a suitable solvent ismixed with the carbonaceous material to form a solution or a wet slurry.In one embodiment, the carbonaceous material is heated in a solid phaseand/or in a dry state. In another embodiment, the carbonaceous materialis mixed with water or another suitable solvent to form a solution or awet slurry prior to heating.

The carbonaceous material is heated at a pressure which is sufficient torelease a tar, or oil, from within the carbonaceous material. The tar,or oil, is an organic material which is derived from the carbonaceousmaterial. In one embodiment, the heating of the carbonaceous material iscarried out at a pressure of less than about 5 atmospheres. In anotherembodiment, the heating of the carbonaceous material is carried out at apressure of from about 1 to about 5 atmospheres.

The carbonaceous material is heated to a temperature effective torelease tar, or oil, from the carbonaceous material. In one embodiment,the carbonaceous material is heated to a temperature of from about 300°C. to about 500° C. In another embodiment, the carbonaceous material isheated to a temperature of from about 350° C. to about 450° C. In yetanother embodiment, the carbonaceous material is heated to a temperatureof from about 375° C. to about 425° C.

At temperatures lower than about 300° C., an insufficient amount of taris released from the carbonaceous material and/or the tar released willbe less complex in composition, and therefore less hydrophobic than tarreleased at a temperature of greater than 300° C. and less than 500° C.At temperatures higher than about 500° C., the tar released from thecarbonaceous material will not adequately coat the carbonaceous materialor at least a portion of the carbonaceous material, e.g., reaction ofthe tar is promoted above these temperatures.

The heating of the carbonaceous material is accomplished using anysuitable heating method and/or heat source. Examples of suitable heatingmethods and/or heat sources include pyrolysis, flash pyrolysis, partialoxidation, microwave energy, other conventional heating methods and/orheat sources or a combination comprising at least one of the foregoing.

In one embodiment, the heating of the carbonaceous material isaccomplished using microwave energy. The microwave energy used to heatthe carbonaceous material is supplied by a microwave energy generationdevice, such as a magnetron in a microwave oven. Wave energy generatedby the magnetron is transferred to the carbonaceous material using forexample, a wave guide or a wave tube.

The amount of microwave energy and the frequency of the microwave energyare selected to release the tar from the carbonaceous material at adesired temperature. In one embodiment, the microwave energy may begenerated in a range of from about 100 kilo Watt per pound (kW/lb) toabout 1,000 kilo Watt per pound (kW of power per lb of carbonaceousmaterial). In another embodiment, the frequency of the microwave energygenerated is about 800 MHz or about 2.45 GHz. The heating of thecarbonaceous material is carried out in the presence or absence of aresonator.

Microwave energy is transferred through the carbonaceous materialelectro-magnetically, not as a convective force or a radiative force.Therefore, the rate of heating is not limited by surface transfer, andthe uniformity of heat distribution is greatly improved. Heating timescan be reduced to less than 1% of that required using other heatingtechniques. In one embodiment, the heating of the carbonaceous materialwith microwaves is precisely controlled with respect to the amount ofheat applied, such that a precise temperature may be maintained at alltimes. In other words, substantially all portions of the carbonaceousmaterial are exposed to the same temperature. For example, particles ofthe carbonaceous material form aggregates, or “lumps”. The center ofeach “lump” of carbonaceous material is at the same temperature as thesurface of that lump. Thus, the tar released from the carbonaceousmaterial, under the effect of the heat generated by microwaves, is notsubjected to any temperatures higher than that which is needed torelease the tar. In addition, since the uniformity of heat distributionis improved due to the generation of the microwave energy, the tar isreleased from the carbonaceous material more uniformly.

The carbonaceous material is heated in the presence or absence ofadditives, such as additional tar, which increase the hydrophobicity ofthe carbonaceous material or otherwise enhance the separation ofcarbonaceous material from ash. In one embodiment, the mixture ofcarbonaceous material and the tar is devoid of tar from any sourceexternal to the carbonaceous material, i.e., not already present withinthe carbonaceous material prior to heating or which is not derived fromthe particular carbonaceous material used in the method upon heating. Inthis embodiment, the only tar present in the mixture of the carbonaceousmaterial and the tar is the tar that was released from the carbonaceousmaterial upon heating.

In another embodiment, additional tar from an external source other thanthe carbonaceous material is added to the carbonaceous material prior toheating and/or to the mixture of the carbonaceous material and the tarformed during and/or after heating the carbonaceous material. In anotherembodiment, the additional tar is derived from a carbonaceous materialand/or is a biomass material.

The mixture of the carbonaceous material and the tar is cooled byremoving, discontinuing or lowering the heat temperature from the heatsource described above and/or by transporting the mixture ofcarbonaceous material and the tar to a region which is not subjected tosuch heat from said heat source. In one embodiment, the mixture of thecarbonaceous material and the tar is cooled to a temperature of betweenabout 0° C. and about 300° C. In another embodiment, the mixture of thecarbonaceous material and the tar is cooled to a temperature of betweenabout 0° C. and about 200° C. In yet another embodiment, the mixture ofthe carbonaceous material and the tar is cooled to a temperature ofbetween about 0° C. and about 100° C. In one embodiment, the cooling ofthe mixture of the carbonaceous material and the tar directly followsthe heating of the carbonaceous material.

Upon cooling of the mixture of the carbonaceous material and the tar, atleast a portion of a surface of the carbonaceous material is coated withat least a portion of the tar. The tar released from the carbonaceousmaterial is hydrophobic in nature. The resulting tar-coated carbonaceousmaterial is thus a surface-modified carbonaceous material. The coatedtar increases the number of hydrophobic functional groups on the surfaceof the carbonaceous material, thereby increasing the overallhydrophobicity of the surface of the carbonaceous material. Theincreased hydrophobicity of the surface of the carbonaceous materialimproves the separation of the hydrophobic tar-coated carbonaceousmaterial from the hydrophilic ash in a subsequent ash removal process.

In one embodiment, a surface of the tar-coated carbonaceous material isabout 10% to about 80% more hydrophobic than the surface of thecarbonaceous material prior to being subjected to said heating, coolingand coating. In another embodiment, a surface of the tar-coatedcarbonaceous material is about 20% to about 80% more hydrophobic thanthe surface of the carbonaceous material prior to being subjected tosaid heating, cooling and coating. In yet another embodiment, a surfaceof the tar-coated carbonaceous material is about 30% to about 80% morehydrophobic than the surface of the carbonaceous material prior to beingsubjected to said heating, cooling and coating.

In another embodiment, the carbonaceous material is partially coatedwith the tar released from the carbonaceous material. In yet anotherembodiment, the carbonaceous material is uniformly coated with the tarreleased from the carbonaceous material. In still another embodiment,the carbonaceous material is heated using microwave energy and isuniformly coated with the tar released from the carbonaceous material.In still yet another embodiment, the carbonaceous material is crushedcoal which is heated using microwave energy and uniformly coated withthe tar released from the carbonaceous material.

The tar-coated carbonaceous material is subsequently subjected to atleast one ash removal process with or without the use of additives toenhance the separation of the tar-coated carbonaceous material from theash. In one embodiment, the tar-coated carbonaceous material is devoidof any additive to enhance the separation of the carbonaceous materialfrom the ash. In another embodiment, the tar-coated carbonaceousmaterial further comprises at least one additive to enhance theseparation of the tar-coated carbonaceous material from the ash.

Referring back to FIG. 1, in one embodiment, the method furthercomprises removing ash from at least a portion of the tar-coatedcarbonaceous material. The tar-coated carbonaceous material is subjectedto any ash removal process suitable to separate the tar-coatedcarbonaceous material from the ash mixed therewith on the basis of thedifferences between hydrophobic and hydrophilic surface properties. Inone embodiment, removing ash from the tar-coated carbonaceous materialis accomplished by a hydro-treatment. The hydro-treatment involveswashing the tar-coated carbonaceous material with water or anothersuitable solvent, for example in a separation or flotation column. Asthe tar-coated carbonaceous material is washed, e.g., with water, thehydrophobic tar-coated carbonaceous material is separated from thehydrophilic ash mixed therewith.

The method described herein allows for greater removal of ash from acarbonaceous material when compared to a carbonaceous material which isnot subjected to said method. In one embodiment, the tar-coatedcarbonaceous material is subjected to a hydro-treatment to remove ash inwhich a total ash content of the tar-coated carbonaceous material isreduced to about 0% to about 50%. In another embodiment, the tar-coatedcarbonaceous material is subjected to a hydro-treatment to remove ash inwhich a total ash content of the tar-coated carbonaceous material isreduced to about 30% to about 50%. In yet another embodiment, thetar-coated carbonaceous material is subjected to a hydro-treatment toremove ash in which a total ash content of the tar-coated carbonaceousmaterial is reduced to about 0% to about 30%. In still anotherembodiment, the tar-coated carbonaceous material is subjected to ahydro-treatment to remove ash in which a total ash content of thetar-coated carbonaceous material is reduced to about 5% to about 20%. Instill yet another embodiment, the tar-coated carbonaceous material issubjected to a hydro-treatment to remove ash in which a total ashcontent of the tar-coated carbonaceous material is reduced to about 15%or less.

Referring to FIG. 2, a system for treating a carbonaceous material isprovided. A system 10 for treating a carbonaceous material comprises aheating region 20, the heating region 20 being operative to heat acarbonaceous material (not shown) to form a mixture of the carbonaceousmaterial and a tar; and a cooling region 30, the cooling region 30 beingoperative to cool the mixture of the carbonaceous material and the tarand to coat at least a portion of a surface of the carbonaceous materialwith at least a portion of the tar to form tar-coated carbonaceousmaterial. The cooling region 30 is disposed downstream of the heatingregion 20.

In one embodiment, the system 10 further comprises a carbonaceousmaterial processing column 40 which contains the carbonaceous materialand a transport system 50 which transports the carbonaceous material tothe heating region 20 and from the heating region 20 to the coolingregion 30. In another embodiment, the transport system 50 is a conveyorbelt.

In one embodiment, the system 10 further comprises a heating unit 60,which supplies heat to the heating region 20. In one embodiment, theheating unit 60 controls the heat supplied to the heating region 20. Inanother embodiment, the system 10 further comprises an optionalcollecting region 70. The collecting region 70 collects the tar-coatedcarbonaceous material subsequent to the heating, cooling and coating ofthe carbonaceous material in the heating region 20 and cooling region30, respectively. The collecting region 70 is disposed downstream of theheating region 20 and the cooling region 30.

In one embodiment, the system 10 further comprises a feedback loop 80.The feedback loop 80 senses the temperature in the heating region 20 andsupplies this information to the heating unit 60. The heating unit 60uses information from the feedback loop 80 to regulate the temperaturein the heating region 20.

In one embodiment, the system 10 further comprises an ash removal region90 in which ash is removed or separated from the tar-coated carbonaceousmaterial. The ash removal region 90 is disposed downstream of theheating region 20 and the cooling region 30, as well as the optionalcollecting region 70.

In one embodiment, the system 10 further comprises additional equipmentincluding, but not limited to, feed hoppers, crushers, grinders, mixers,conical separators, control units, cooling units, collection units,transport devices, shredders, heaters, screw feeders and/or otherrelated equipment.

The methods and systems described herein pre-treat the carbonaceousmaterial using tar released or derived from the carbonaceous materialitself to partially or uniformly coat the carbonaceous material. Theresulting surface-modified, tar-coated carbonaceous material has anincreased overall hydrophobicity, which improves the separation of ashfrom carbonaceous materials which have undesirably high ash contents inan ash removal process. The methods and systems described herein therebymake such ash-containing carbonaceous materials suitable for subsequentuse in a process which uses low ash coal, e.g., to generate energy. Inthis manner, the methods and systems provided herein allow for the useof relatively high-ash containing carbonaceous materials which wouldotherwise be rendered unsuitable due to their high ash content. Themethods and systems described herein are also used to treat carbonaceousmaterials with or without the use of additional tar from an externalsource other than the carbonaceous material and/or with or without theuse of other additives.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

1. A method for treating a carbonaceous material, comprising: heating,with electromagnetic energy in a heating region, a carbonaceous materialto form a mixture of the carbonaceous material and a tar; cooling, in acooling region, the mixture of the carbonaceous material and the tar;and coating a surface of the carbonaceous material with at least aportion of the tar to form a tar-coated carbonaceous material.
 2. Themethod of claim 1, wherein the carbonaceous material comprises coal. 3.(canceled)
 4. The method of claim 1, wherein heating the carbonaceousmaterial comprises heating with microwave energy in the heating region.5. (canceled)
 6. (canceled)
 7. (canceled)
 8. The method of claim 1,wherein a tar coating on a surface of the tar-coated carbonaceousmaterial is substantially more hydrophobic than the surface of thecarbonaceous material prior to being subjected to said method. 9.(canceled)
 10. The method of claim 1, comprising removing ash from thetar-coated carbonaceous material using a liquid wash system, wherein atar coating on the tar-coated carbonaceous material helps the liquidwash system to remove the ash.
 11. A system for treating a carbonaceousmaterial, comprising: a heating region, wherein the heating regioncomprises an electromagnetic energy source configured to heat acarbonaceous material to form a mixture of the carbonaceous material anda tar; and a cooling region downstream from the heating region, whereinthe cooling region comprises a cooling source configured to cool themixture of the carbonaceous material and the tar, and to help form a tarcoating on a surface of the carbonaceous material with the tar to form atar-coated carbonaceous material.
 12. The system of claim 11, whereinthe carbonaceous material comprises coal.
 13. The system of claim 11,wherein the heating region is operative to heat the carbonaceousmaterial to a temperature of from 300° C. to 500° C.
 14. The system ofclaim 11, wherein the electromagnetic energy source comprises amicrowave energy source configured to output microwave energy to heatthe carbonaceous material.
 15. The system of claim 11, wherein thecarbonaceous material further comprises at least one additive.
 16. Thesystem of claim 11, wherein the carbonaceous material further comprisesadditional tar, the additional tar being from an external source otherthan the carbonaceous material.
 17. The system of claim 16, wherein theadditional tar is a biomass material.
 18. The system of claim 11,wherein the tar coating on a surface of the tar-coated carbonaceousmaterial is substantially more hydrophobic than the surface of thecarbonaceous material prior to being coated with the tar.
 19. The systemof claim 11, wherein carbonaceous material has a total ash content of30% to 50%.
 20. The system of claim 11, comprising an ash-removal regiondownstream of the cooling region, wherein the ash-removal regioncomprises a liquid wash system configured to remove ash.
 21. The systemof claim 20, wherein the liquid wash system comprises a water washsystem.
 22. The system of claim 21, wherein a hydrophobic characteristicof the tar coating of the tar-coated carbonaceous material and ahydrophilic characteristic of the ash helps the water wash system toremove the ash.
 23. A system, comprising: a heating region configured toheat a carbonaceous material having ash and tar to form a mixture of thecarbonaceous material and the tar; a cooling region downstream from theheating region, wherein the cooling region is configured to cool thecarbonaceous material, the ash, and the tar to help form a tar coatingof the tar on a surface of the carbonaceous material to form atar-coated carbonaceous material; and an ash-removal region downstreamof the cooling region, wherein the ash-removal region comprises a liquidwash system configured to remove the ash, and the tar coating helps theliquid wash system to remove the ash.
 24. The system of claim 23,wherein the liquid wash system comprises a water wash system.
 25. Thesystem of claim 24, wherein a hydrophobic characteristic of the tarcoating of the tar-coated carbonaceous material and a hydrophiliccharacteristic of the ash helps the water wash system to remove the ash.26. The system of claim 23, wherein the heating region comprises anelectromagnetic energy source configured to apply an electromagneticenergy to heat the carbonaceous material having the ash and the tar. 27.The system of claim 26, wherein the electromagnetic energy sourcecomprises a microwave energy source configured to apply microwave energyto heat the carbonaceous material having the ash and the tar.